The present invention relates to fastener inserts and, more particularly, to fastener inserts including a cold head stamped detent to form selectively removable tangs, an apparatus for cold head stamping fastener inserts and methods of manufacturing cold head stamped fastener inserts.
Fastener inserts of varying design for maintaining a fastener within a tapped hole or nut assembly are commonly employed. The use of such fastener inserts offer many advantages including, by way of non-limiting example, providing a more balanced distribution of dynamic and static loads throughout the length of engagement between fasteners and the substrate.
To facilitate the disposition of the fastener insert within a tapped hole or nut, often such inserts are provided with a selectively removable tang. The tang typically includes a notch which is milled, sheared, cut or ground into the insert which allows the tang to be broken off. Once the fastener insert is properly positioned within the tapped hole or nut, pressure is exerted on the tang which causes the tang to break away from the fastener insert body and provide an unencumbered passageway for the insertion of a fastener.
The notch on the removable tang has heretofore been formed via milling, shearing, cutting or grinding using a notch cutter or similar tool prior to coiling the wire. In order to carry out the notching step, the wire must be stopped in the middle of the cycle and prior to the coiling step which adds to the time and expense of manufacturing. While the invention of EP 1060812 A2 attempts to address certain problems associated with stopping or significantly slowing down the production process, this document appears to relate to fastener inserts formed from pre-spooled or pre-rolled wires including milled or sheared notches. As a result of notching and rolling the wire and subsequently coiling the wire, a variation on the insert outside diameter and length can result when utilizing different lots or reels of stainless steel wire. Thus, pre-forming the notch on a whole reel of the material could result in processing problems during the coiling operation. This is based on the fact that if the insert diameter or insert length changes due to variation in the wire spring back, the pre-determined location of the notch will not meet location requirements for proper tang break-off after installation. The helically coiled insert will not be dimensioned correctly. The whole reel of pre-notched wire will have to be scrapped.
Another critical element that can result in material damage or losses is based on the fact that the majority of the wire utilized to manufacture the helically coiled inserts are of small diameter in the areas of 0.010xe2x80x3 to 0.050xe2x80x3. Based on this fact, a pre-notched reel of wire contains thousand and thousands of strands and tens of thousands of notches. It would be very easy for this wire to be tangled, nicked or to break at any of the pre-notched locations if not handled with extreme caution and care. This can further result in additional material losses or operating and set up problems during the coiling operation.
Further, there are certain safety issues introduced into the manufacturing process as a result of milling, such as metal chip formation. Sharpening of the milling apparatus also may pose certain risks.
Yet another problem with heretofore known fastener inserts is the inability to identify similarly shaped inserts from one manufacturer to the next. This is especially problematic where fastener insert quality varies among manufacturers.
In view of the foregoing, a notched fastener insert which solves one or more of the enumerated problems is desirable.
The present invention therefore relates to a method of manufacturing an insert comprising the steps of:
a) providing a wire;
b) cold head stamping the wire to form a detent in said wire;
c) coiling the wire to form a helically coiled body; and
d) bending an end of said wire in proximity to said detent to provide a selectively removable tang.
The present invention further relates to a fastener insert comprising:
a wire body having a plurality of convolutions;
at least one detent cold formed into said wire body; and
a selectively removable tang extending from said body in proximity to said at least one detent.
Still another aspect of the present invention is a method of marking fastener inserts, wherein the method generally comprises the steps of:
a) providing a wire;
b) cold head stamping marking on said wire; and
c) coiling the wire to form a helically coiled body.
The present invention further relates to a fastener insert comprising:
a wire body having a plurality of convolutions; and
a marking stamped into said wire body to provide an identifier on said insert.
An apparatus for cold head stamping wire to be formed into fastener inserts is also provided in accordance with the teachings of the present invention. The cold head stamping apparatus for use in association with wire comprises:
a fixture;
a selectively extendable and retractable stamping die supported by said fixture for stamping a detent into said wire; and
an actuator for intermittently extending and retracting said stamping die.
In contrast to milling, the cold head stamping of a detent in accordance with the teachings of the present invention, eliminate the issues of metal chip formation and ejection and repeated tool sharpening. Further, the cold head stamping process can be carried out before or during the coiling step which is preferred and gives rise to shorter production cycle times. Additionally, as a result of the cold head stamping, the notch itself is improved to give a cleaner, e.g. burr free, more efficient break point between the tang and the body of the fastener insert.
The ability to mark the fastener inserts with an identifier designating the manufacturer, material or other pertinent information can have a significant impact on quality control considerations.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.